Grid shows Hour Angle (HA) using your longitude and the selected time.
3D Planetarium Controls
Drag mouse to rotate the sky
Scroll wheel to zoom in/out (auto-adjusts magnitude to show fainter stars when zoomed in)
Click a star/planet for info
Right-click magnitude slider for custom values
Adjust magnitude filter to show/hide faint stars
Toggle "Auto-adjust magnitude on zoom" to link zoom level with star visibility
Set your latitude/longitude for local sky orientation
Toggle stars/planets visibility
Toggle horizon grid (altitude/azimuth with N/E/S/W)
Toggle equatorial grid (HA/DEC: Hour Angle and Declination)
Toggle the ecliptic line
Reset view to default orientation and zoom
Use the Time control to preview the sky at any date/time; the grid labels show Hour Angle (HA).
Tip: Focus the Time box and press Arrow Up/Down to adjust with rollover. Move the caret over year/month/day/hour/minute to change that unit. If caret isn't available, use Shift (hour), Ctrl (day), Alt (month), or Ctrl+Shift (year).